Most BMW models have a 7-year lifecycle, and typically get the LCI (lifecycle impulse) refresh at the fifth model year (making 4 model years with the initial design and 3 model years with the LCI). There are exceptions, though, such as the E65 7-Series, which was updated (and much improved) after just 3 years due to negative response to the trunk styling. And it's possible that BMW may be pushing the LCI up to the fourth model year more often, even absent a controversy like the 7 "Bangle Butt".

From what I've read, it appears that the 5 sedan and 5GT are getting their LCIs concurrently this calendar year (carrying a 2014 model year designation), which is a little early for the sedan (it came out 5-6 months after the GT I believe?) but probably about right for the GT, which started with a 2010 model year. This would freshen up the 5GT in light of the new 3GT, which incorporates some of the newer, more modern design cues not found in the existing 5 lineup.

I was under the impression that the new-style "red laser" iDrive and fully-digital dashboard were present in the 2013 MY GT, at least those produced after a certain date, but if not they would almost certainly be in the 2014 MY LCI.